Field of the Invention
Embodiments of the current invention relate to environmental sensor signal processing.
Description of the Related Art
Sensors able to detect environmental changes are in demand for a number of applications. For example, detection of changes in temperature, pressure, or various analytes in contact with the sensor (including moisture or gases in the air, etc.), is desirable for applications such as indoor and outdoor climate detection and control, process control, biometrics, medical uses, and much more. However, the usefulness of these sensors is limited by their ability not only to accurately and precisely measure stimuli, but their ability to detect and measure those stimuli in both the short and long term. Response time and settling time are very important factors when trying to measure humidity for applications where immediate detection is necessary, such as breathing sensors. The response time or time constant of a sensor is often measured as the time it takes for 63% of an equilibrium value of a sensor response to occur from no load to a step change in load. Settling time is often measured as the time it takes for a sensor to reach a stable output once it is turned on. Sensors must also be able to maintain long-term stability and measurement, and should demonstrate low hysteresis. Many previous thin-film direct-current resistive-based sensors have been plagued with poor performance as a result of very high hysteresis, low stability, and low accuracy.